Best open-source alternatives to Microsoft Teams

OpenClaw is a personal AI assistant designed to run on the user's own devices rather than as a centralized cloud service. It is aimed at individuals who want an assistant that can communicate through existing messaging platforms, handle voice interactions on supported devices, and provide a controllable live canvas workspace. The project centers on a gateway control plane that manages sessions, channels, tools, and events, while assistants operate through isolated workspaces and per-agent sessions. It supports a wide range of messaging channels, includes onboarding-oriented setup, and offers companion apps for Windows, macOS, and mobile platforms. The README also emphasizes security controls for direct messages, local allowlists, and safe exposure practices.

Rocket.Chat is an open-source communications platform aimed at organizations that need secure internal and external collaboration. The README positions it as a team messaging solution for companies, public-sector users, and regulated environments where privacy, compliance, and control over data are important. It supports multiple deployment models, including self-hosted, cloud, and air-gapped setups, and highlights workspace management, federation, identity management, encryption, and role- and attribute-based access control. The project also includes desktop and mobile apps, an apps marketplace and Apps-Engine for extensions, and API and developer documentation for integration and customization.

Mattermost is an open core collaboration platform designed for teams that want to self-host their communication and workflow stack. It provides a web-based interface and native clients for desktop and mobile, and is positioned for use cases such as DevSecOps, incident resolution, and IT service desk operations. The project is the primary source for core platform development and is implemented in Go and React. The software runs as a single Linux binary and depends on PostgreSQL for storage. The README emphasizes deployment flexibility, with installation paths for Docker, Ubuntu, tar archives, Kubernetes, and Helm. It also points users to product and developer documentation, and highlights a broad integration surface including webhooks, slash commands, drivers, web services, apps, and plugins.

Jitsi Meet is an open source video conferencing project designed for people who want to run or use modern online meetings. It is presented as a browser-based service, with companion mobile apps and SDKs for integrating meeting functionality into other products. The README emphasizes usability across current browsers and highlights core conferencing capabilities such as HD audio/video, chat, polls, reactions, and virtual backgrounds. The project is aimed both at end users who join meetings on the public service and at organizations that want to deploy their own instance. Deployment guidance points to the Jitsi handbook, with Debian packages, Docker-based deployment, and source builds available for self-hosting. The README also mentions Jitsi as a Service (JaaS) for teams that prefer a managed enterprise offering rather than operating the platform themselves.

Zulip is an open-source team chat platform designed to help organizations manage both real-time and asynchronous communication in a more structured way than traditional chat apps. Its signature feature is topic-based threading, which keeps conversations organized and makes it easier for distributed teams to follow multiple discussions without losing context. The project is aimed at teams, open-source communities, and other organizations that need productive group communication. The README highlights self-hosting on Ubuntu or Debian Linux, deployment via Docker, and hosted cloud options through Zulip Cloud. It also emphasizes a large contributor community and extensive documentation for both code and non-code contributions, suggesting a mature project with a broad user and developer ecosystem.